Medical retrieval devices generally are used to retrieve biological and foreign material including stones from the body. Such medical retrieval devices may be used through an endoscope or a laparoscope.
One type of known medical retrieval device has a sheath and a retrieval assembly such as a basket that is movable in and out of the sheath. When the basket is within the sheath, the basket assumes a collapsed, reduced diameter profile. When the sheath is retracted relative to the basket or the basket is moved beyond the end of the sheath, the basket expands to a relatively larger diameter than when the basket is enclosed within the sheath. Generally, the contour of known baskets is round or oval and is formed by a plurality of legs.
With many known retrieval devices, materials are used in the retrieval assembly to enhance its rigidity. However, rigid materials used to enhance strength do so at the expense of flexibility. The retrieval assembly must, on the one hand, be sufficiently strong to dilate the body tract and, on the other hand, be sufficiently flexible to negotiate body tracts having small diameters, tortuous pathways and irregular lumens. Moreover, flexible retrieval assemblies can more easily capture large stones through the gaps in the legs of the retrieval assembly, than can rigid retrieval assemblies. When flexible materials are used in the retrieval assembly, however, rigidity and strength are compromised.